A colloidal solution is subjected to an electrical field. The particle move towards anode. The coagulation of same sol is studied using `NaCl, BaCl_(2)` and `AlCl_(3)` solutions. Their coagulating power should be

Options

A. `NaCl gt BaCl_(2) gt AlCl_(3)`
B. `BaCl_(2) gt AlCl_(3) gt NaCl_(3)`
C. `AlCl_(3) gt BaCl_(2) gt NaCl`
D. `BaCl_(2) gt NaCl gt AlCl_(3)`

Explanation

To determine the coagulating power of the given salts (NaCl, BaCl₂, and AlCl₃) on a colloidal solution, we need to consider the valency of the cations present in these salts and how they affect coagulation.

### Step-by-Step Solution:

1. **Understanding Coagulation**:
Coagulation is the process where colloidal particles aggregate to form larger particles, which can then settle out of the solution. The coagulating power of a substance is influenced by the charge and valency of the ions present.

2. **Identifying Cations and Their Valencies**:
- **NaCl**: Contains Na⁺ (valency = 1)
- **BaCl₂**: Contains Ba²⁺ (valency = 2)
- **AlCl₃**: Contains Al³⁺ (valency = 3)

3. **Relation Between Valency and Coagulating Power**:
The coagulating power of a cation is directly proportional to its valency. Higher valency cations have a greater ability to neutralize the charge on colloidal particles, leading to more effective coagulation.

4. **Ranking the Cations**:
- Al³⁺ (from AlCl₃) has the highest valency (3), thus it has the highest coagulating power.
- Ba²⁺ (from BaCl₂) has the second highest valency (2), thus it has moderate coagulating power.
- Na⁺ (from NaCl) has the lowest valency (1), thus it has the least coagulating power.

5. **Conclusion**:
Based on the valency of the cations, the coagulating power of the salts can be ranked as follows:
- **AlCl₃ > BaCl₂ > NaCl**

### Final Answer:
The coagulating power of the salts in order is:
**AlCl₃ > BaCl₂ > NaCl**

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